The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefore.
This patent application is co-pending with two related patent applications filed on the same date, entitled: COMPACT DRIVE SHAFT FLOATING SEAL SYSTEM, and AXIALLY PRESSURE BALANCED FLOATING SEAL SYSTEM, both having the same inventors as this patent application.
(1) Field of the Invention
The present invention relates to sealing assemblies used on rotating shafts and more particularly, relates to a radially pressure balanced floating seal system used on a drive shaft.
(2) Description of the Prior Art
O-ring seals are commonly used to seal rotating shafts used in vehicles or machinery. For example, in an existing torpedo tail cone assembly 10, FIG. 1, the drive shaft 12 of the torpedo is typically sealed with an O-ring seal system having a seal housing 14 and an O-ring seal 15 within a groove in an internal annular surface of the housing 14. The seal housing 14 is located within the tail cone housing 16 near the bearing 18. When the torpedoes have stable and concentric shaft bearing mounts relative to the seal, non-floating seal housings can be used, and these housings will still maintain reasonable clearance to prevent rubbing between the shaft 12 and the seal housing 14. Larger shafts that are mounted soft enough to move or float relative to the seal housing require floating seal housings. The floating seal housing moves with the drive shaft 12 generally in a radial direction as indicated by arrow 2 maintaining clearance of the shaft 12 and preventing the shaft 12 from rubbing against the seal housing 14.
In some types of O-ring sealing systems (not shown), two O-rings are used on each side of a lubricant recess containing oil or another type of lubricant for lubricating the O-ring seals. Canting (or slanting) the O-rings within the seal housing facilitates active lubrication of the seals as the shaft rotates and improves the life span and capability of the seals. In floating seal housings, however, standard canted O-ring seals have resulted in an unbalanced radial or side force on the seal housings. If the system is not axially pressure balanced, the net axial force in a pressurized environment may not permit the. floating seal housing to float freely in the radial direction. Thus, the unbalanced radial or side force often cannot overcome the radial friction force due to axial pressure, and the shaft will rub against the housing when the floating seal housing is unable to float in response to the unbalanced radial force.
One object of the present invention is a radially pressure balanced seal housing minimizes the potential of rubbing and failure.
Another object of the present invention is a radially pressure balanced seal housing in which the sealing members are effectively lubricated.
A further object of the present invention is a radially pressure balanced seal housing having a minimized seal length.
The present invention features a floating seal system for sealing a rotating shaft. The floating seal system comprises an outer seal housing having an internal recessed region and an inner seal housing received in the internal recessed region. The outer seal housing and the inner seal housing define an aperture for receiving the shaft. The inner seal housing is movable in a generally radial direction with respect to the outer seal housing allowing radial movement of the shaft.
The inner seal housing includes an annular internal surface defining the aperture through the inner seal housing, a lubricant recess formed within the annular internal surface of the inner seal housing for receiving lubricant and for holding the lubricant against the shaft, and first and second sealing members retaining grooves formed within the annular internal surface of the inner seal housing. First and second inner sealing members are disposed within respective first and second sealing member retaining grooves. The first and second sealing member retaining grooves and the first and second inner sealing members are double canted such that the first and second inner sealing members are lubricated by lubricant from the lubricant recess and are radially balanced with respect to the shaft.
In the preferred embodiment, a retaining member coupled to the outer seal housing retains the inner seal housing within the internal recessed region while allowing the inner seal housing to move in the generally radial direction. An end annular sealing member is disposed between an end face of the inner seal housing and a side of the internal recessed region, for sealing the inner seal housing against the outer seal housing. One or more torque members extend from the outer seal housing into engagement with the inner seal housing for preventing rotation of the inner seal housing relative to the outer seal housing. The inner seal housing preferably includes one or more torque member receiving regions and respective elastomer bushings in the torque member receiving regions for receiving the torque member thus balancing as the sides for radial loading. The torque member receiving regions preferably includes a clearance under the torque members for allowing the inner seal housing to move in the generally radial direction. The at least one torque member can include multiple discrete torque members or one uniformly distributed (360 degree) torque member.
According to the preferred embodiment of the inner seal housing, the first and second sealing member retaining grooves each have a first groove portion and a second groove portion. The first groove portion and the second groove portion of the first sealing member retaining groove each have an end lying in a first radial plane generally orthogonal to an axis of the inner seal housing and form an angle with respect to the first radial plane. The first groove portion and the second groove portion of the second sealing member retaining groove each have an end lying in a second radial plane generally orthogonal to the axis of the inner seal housing and form an angle with respect to the second radial plane.
In one preferred embodiment of the inner seal housing, the lubricant recess lies in a third radial plane generally orthogonal to-the axis of the inner seal housing. In another preferred embodiment, the lubricant recess has a first recessed portion and a second recessed portion. The first recessed portion and the second recessed portion of the lubricant recess each have an end lying in a third radial plane generally orthogonal to the axis of the inner seal housing and form an angle with respect to the third radial plane. The first recessed portion and the first groove portions of the first and second sealing member retaining grooves are generally parallel, and the second recessed portion and the second groove portions of the first and second sealing member retaining grooves are generally parallel.